Hi,
Personally I think the terra preta concept is quite appealing with the aim of making a stable humus rich soil with excellent nutrient and water retention.

My main problem with the concept is that it is quite resource heavy. Composting needs a lot of woody/organic material to compensate for the nitrogen in urine and faeces, and in this case we also add charcoal. My estimation would be ~100 kg of wood to make ~20 kg of charcoal (would that be enough?) and 200 kg of wood for the composting - per person per year. And then you need to have (make or buy) the lactofermentation mixture + addition of sugars to feed them in the excreta mixture.

All this together makes it difficult to imagine an upscaling situation. 300 kg of woody material per person per year...woody biomass is not really available in huge quantities in most countries...I think Ralf's answer would be to grow bamboo with the greywater which could in turn be used for the composting, but I don't know how far that would take us.

The lactofermentation of feces seem quite good for sanitization though - Gina Itchon did some experiments in the Philippines with good inactivation of pathogens including ascaris:
www.drytoilet.org/dt2012/full_papers/5/Gina_S_Itchon.pdf

Then the question arises how much bacterial mix will be needed per person per year to sanitize the mixture? And how much sugars are needed to:
a) grow this amount of bacterial mix?
b) feed them once they are mixed into excreta?

I saw there was another interesting paper from Ralf's group at the dry toilet conference on lactofermenting excreta which showed best results with 10% wet-weight addition of lactofermenting bacteria, 10% wet-weight addition of molasses (to feed the bacteria) and 10% w/w biochar to the excreta mixture.
www.drytoilet.org/dt2012/full_papers/4/Asrat_Yemaneh.pdf

For a total human feces+urine prodcution of ~500 liters per year, the 10% wetweight would translate to ~50 liters of lactofermenting bacteria, ~50 liters of molasses and ~50 kg of biochar per person per year. What does this represent in terms of costs/resources? And that would be before the composting step.

To reduce the volume to treat (and the resources needed) it seems separate feces collection is still valuable, although this is not what most users want...

If both urine and feces are to be lactofermented with biochar + composted at scale our society would need to make TPS a top priority. Maybe the value of the terra preta will be so high that it covers the resources needed for processing? Is terra preta sold in Germany yet?

There seems to be a lot to research still, but I think it is cool that Ralf's group is taking on unconventional stuff.

Regards
Linus

Thanks Elisabeth, for opening this discussion.

I admit I know little about terra preta sanitation, and have not cared to take a deeper look so far, because the whole issue had a esoteric touch for my taste. But perhaps this discussion may help changing this perception

Two questions/comments:

1) This lactic acid fermentation, is that the same thing as "effective microorganism" (EM) that are quite popular in parts of Asia and Latin America?

2) As I understand, the addition of charcoal to the toilet / soil is a central element of the concept. This is where I have the greatest doubts about the concept. In many regions, the use of charcoal for sanitation would be expensive (thus probably will not happen) and also very detrimental to the environment.
As has been pointed out before, charcoal is an important energy source in many poorer regions of this globe, using it in addtion for sanitation would thus be costly. Another important issue is that the use of charcoal as energy source is a huge problem in many regions of the world, as it causes deforestation and loss of biodiversity as wood from primary forests is often used for producing charcoal. This happens especially in regions where poor people are living. Promoting use of charcoal in sanitation would therefor exacerbate these problems.

Best, Florian

(Dear Hugo: you suggested to Hanns-André to move your discussion to e-mail. Please don't do that, as your discussion is indeed interesting for many people. Rather, I have re-arranged the threads. I have moved the part on the Terra Preta Conference in Hamburg to Events and to WG 5, and I have re-named this thread to match better what we discussed.)

Dear all,
It is good that we are having this conversation about Terra Preta Sanitation. I would like to go back to some points Ralf made:

Ralf said:

We can also call it Black Earth but why should all be in English? This is the inspiration of the probably most sucessful sanitation and biowaste management ever on Earth. In order to honour those Indios we use this name.

Ha-ha, isn't it funny to use a Portuguese term to "honor" the Indios (= (language of the conquerers)? For Brazilian people, I believe that Terra Preta sounds exactly the same as for English people Black Earth...

It covers around 10% of the Amazon region around Manaus, not of all the vast Amazonian Rainforests.

What is the significance of Manaus in particular? How can one then know if it is a big area (in the scheme of things) or not? If I am not wrong then Manaus is a city in the center of the Brazilian Amazon, the entire administrative region "Metropolitana de Manaus" has "101,474 km ²" (from Wikipedia), representing 1.5% of the Amazon (7 million km ² according to Wikipedia dt). Today, it has 2 million inhabitants (not for TP reasons but because free trade area, since large-scale computers and flat screens are built there at the expense of the environment).

Now to TP sanitation. Please show me where the hype is? Hardly anybody works on this so far.

To me it is quite a big hype. I say that because in plenty of news articles, it is mentioned (e.g. in that big Geo article from last year) - alongside other, more established technologies. Journalists love it and keep bringing it up as if it would save the world now (the "lost/rediscovered" knowledge of the Indios is saving our world now...). Also e.g. in the SSWM toolbox (www.sswm.info) it (terra preta toilets) is represented side by side the more established toilet types - as if it had already reached the same level of maturity. In my opinion, it is still at a research stage, far from being "proven" at any significant scale in practical applications.

In addition we want to compost urine so we do not need diversion any more, luckily. Urine application mimics chemical agriculture and is a dead end road.

I disagree that urine is a "bad fertiliser", there are plenty of results from countries where it has given them impressive boosts in yield. See the publications by SEI on that topic. See the work of SEI and IFAD in Niger for example (if anyone is interested in the Niger example: just put the name Dagerskog in the search field of the SuSanA library, or click here:
www.susana.org/library?search=dagerskog)
You would argue that these results are only in the short term and that in the longer term, the soil would degrade? Well, nobody recommends to only use urine. Of course it is always better to add as much organic matter (compost) as possible, too. But that doesn't diminish the importance of urine as a cheap, pathogen-free fertiliser, supplying N, P, K, S and other micronutrients.

we should forget about people in more densely populates areas dealing with their own excreta

I agree with that statement.

The well proven fact of endocytosis, the direct uptake of living bacteia like E-coli and Salmonella into plants advises us against direct food production in excreta.

I disagree with this statement completely. Your statement should be taken as the opinion of one expert, but many other experts do disagree. I want to remind the readers that this discussion has already been debated on the forum previously, with very detailed postings by the Swedish expert Hakan Joensson for example (and a discussion on organic agriculture with detailed input from Gerhard Pelzer), see here:
forum.susana.org/forum/categories/17-fer...le-plants-preferably

Finally, let me pose another question, which I think is very important. You speak about Terra Preta Sanitation. Where is the evidence that this process of lacto-fermentation kills the pathogens to a significant degree (in particular the worm eggs)? If not, can it really be called sanitation. Shouldn't sanitation sanitise - at least to some degree (or at least "contain"). How exactly are the worm eggs dealt with in Terra Preta sanitation? Or is your argument that the worm eggs don't need to be killed if one does not use the compost for food production in any case (multi-barrier approach)?

I look forward to reading your replies and the replies of others, too, of course. I think we can all learn a lot here - even if in the end we might have to agree to disagree.

Kind regards,
Elisabeth

Hi Hanns-Andre,

the addition of biochar into the soil helps to keep the soil pH stable, increases the cation-exchange capacity (improving fertilization) and acts as a sponge holding the water at the soil upper layers. On the book "As Terras Pretas de ĺndio da Amazônia Sua Caracterização e Uso deste Conhecimento na Criação de Novas Áreas", Madari et al. (2009) write that the mineralization of black carbon in soil is stimulated by glucose addition and vice versa. So the combination of char and organic matter is the key to carbon sequestration, as char particles smaller than 2mm have a life-time of less than 100 years in subtropical soils (Birds et al. 1999). Other interesting aspect is that Pabst (1991) verified that the humus find at the Belterra Terra Preta (Belterra is a city on the North of Brazil) is six times more stable than the humus find at the surrounding Oxissoil.
If you haven't been there before, please visit this website. It has many interesting videos from the Hamburg University of Technology about Terra Preta Sanitation.

Regarding the manioc, there are two main types and only one have high toxic cyanogenic content. This one (M. esculenta) is still used on the production of flours and alcoholic beverage (through fermentation). The other one (M. utilissima) can be eaten with no poisonous effect after cooking on boiling water. It is difficult to assure that the índios used lacto fermentation on their waste, but it is known that they had knowledge about the fermentation process. From my point of view it is easier to fermentate than to compost (specially in temperate climate) and that is a good point on waste management. I think it would be also possible to recreate TP from well composted waste, but the composting process can demand a lot of work sometimes.

Kind regards,
Hugo

An interesting note to the question - did ever the Indios applied lactic acid fermentation? From the literature data, the staple food of Amazonians was manioc (a carbohydrate rich plant), the bitter cultivars of which had high cyanogenic content. One of the processing techniques for detoxification was soaking of manioc tubers in water, during which lactic acid fermentation occurred. The manioc has also a short term storage capacity after its harvest; therefore, fermentation was an important practice to apply. Some inhabitants of upper and middle Amazon areas were fermenting manioc keeping it burrowed in earth pits lined with leaves for up to 1-2 years. Myers (2004) indicates that the ancient Amazonian population have used the practice of underground crop preservation in silos as well as different types of fermented food and beverages. For example cocoa was obtained via lactic acid fermentation. Some authors like Krieger, 2011 and Pieplow, 2010 indicate that lacto-fermentation was used by Amazonian population not only as a way to process and preserve food waste, but also to process excreta for the purpose of soil enrichment. For example, remnants of big ceramic vessels of 200-300 l discovered in some terra preta sites were presumably being used for fermentation of food waste and excreta. While there is insufficient evidence to prove about the application of lactic acid fermentation for excreta management in Ancient Amazonia, it still can be hypothesized that microbial rich waste was generated during their daily activities that might have been applied to soil or deposited to the middens that in turn have improved the decomposition process.

Hugo, thanks very much for these explanations and the very interesting links you have shared with us! As far as the charcoal issue is concerned, it seems to me that the main argument in our times is carbon sequestration in tropical (and other) soils. Apparently, char is much more resistant to degradation than other soil based carbon compounds (at least that's what the researchers are claiming). I think, with regard to the issue of climate change, that is a very valid argument, but the application of char can only be one aspect of carbon sequestration in soils. From that point of view, almost any kind of ecosan could qualify as 'terra preta'. So, what is the specific definition of terra preta sanitation? Is it the addition of charcoal that makes the difference? Or is it that lactobacterial process? And did the Indios ever use that process? - Of course, these are questions first of all to the organizers of the conference rather than Hugo.

Thanks again, and regards to everybody,

Hanns-Andre

Hi Hanns-Andre, hi all,

Regarding the question about the charcoal, it is impossible to answer without taking in consideration the cultural habits from the pre Columbian civilization. Some Brazilian tribes have different words to describe different types of ash (nowadays). The fire rituals vary a lot from tribe to tribe, being the Kayapós and the Machiguenga considered as the “masters of fire”. It is quite difficult for us to understand and/or explain their culture. In example, potteries were not seeing as simple objects: they were produced from different minerals for different uses. Some ethnics groups would even treat the clay pottery as a tribal member. So let me remark that TP soils are filled with pottery pieces and then it is possible to understand the importance that such groups were giving to these soils. The problem is that even the living tribes in Amazon don’t have the knowledge to reproduce TP soil.

As the creation of TP soil is unknown, we have to deal with hypotheses. I believe that small random glades were extended by means of fire, and such burnings produced a lot of charcoal (combustion of wet wooden mass). Then such glades were used for living purposes and became the known Terra Preta. After some time the Terra Mulata soils were created (on the surroundings) according to some waste management based on in-field burnings, maybe one form of slash and char. As no archeological artifacts are found in Terra Mulata soils, it is believed that such areas were used for agricultural purposes. I do think that biochar was a product of some agricultural management and it was not seen as something scarce.

“Could you give details about the benefits of charcoal in tropical soils, or references, preferably ones that can be looked up on the Internet?”

I am no specialist at the topic, I am more like an enthusiastic . Most of the things I share about TP are based in readings from some Portuguese books from Embrapa and classes I attended during University. In English I would suggest the books and papers from J. Lehmann and W. Sombroek. In internet you can find some interesting basic/short information about Terra Preta and Biochar at www.css.cornell.edu/faculty/lehmann/rese...har/biocharmain.html
The website www.biochar.org contains also lots of information towards charcoal.

Hanns-Andre, please send me an email for more detailed conversation.. I fear we are starting a discussion more about terra preta and charcoal than about the Conference itself (the topic of this thread).
Dear Nadia, nice words and interesting study! Do you have more available details about it? Keep on doing the good work!

Kind regards,
Hugo

Dear Elizabeth, dear all,
As regarding the distribution of terra preta, a map is given in chapter 4 of the book "Amazonian Dark Earths: origin, properties, management Ed by Lehmann et. al. 2003.
(api.ning.com/files/0ajZyv5b7ozZ3KKKbUV-R...E9nt3Upjf/09Kern.pdf
In my opinion, terra preta sanitation approach can improve the management of excreta in UDDT as sanitization time can be reduced and lactofermented faeces contain more nutrients and organic matter than simple dessicated faeces. The faeces can be lactofermented both during the collection stage (while in the toilet) and after it (in closed containers or earth pits). The amount of faeces in UDDT is quite small, but other types of bio-waste (such as cow manure, kitchen waste) can be added. As a separate toilet system, terra preta toilet is still in the course of elaboration we cannot say it is easily accepted or not simple because it was not yet tested except at the experimental stage. I do believe that in both cases - for UDDT system or terra preta toilet there is a need to change the attitude toward excreta management, we have to accept that we take care of our shit and as a reward we receive a valuable fertilizer.
In the experiments with terra preta in Moldova I used as bacterial innoculum sauerkraut and as charcoal I have used waste from charcoal which is produced for grill. Human faeces was the main component, but also have added cow manure, fruit waste and mollases (5-8%). I have observed beneficial effects on plants at 10 % of terra preta in pot experiments- for example even the germination was few days later than the control, the seedlings were stronger, there were more established plants and faster growth rate. During this year the effects of terra preta will be investigated in the field(the application was made during autumn). I think that terra preta conference would be a great opportunity to learn from all the research that was carried out until now in the field and share the experience.
Kind regards,
Nadia Andreev, PhD fellow Unesco IHE

Hi Hugo,

thanks very much for the infos you have given about these terra preta soils. Could you give details about the benefits of charcoal in tropical soils, or references, preferably ones that can be looked up on the Internet? And do you seriously think the Indios were using something like wood gas stoves, or did they just have wood and charcoal in such abundance that they didn't have to worry about a little charcoal deposited in their land?

Here in northern Uganda, some people have little sieves with which they remove pieces of charcoal from the ash in order to reuse them. Charcoal is a commodity with a high value.

Thanks again, Hanns-Andre

Dear all,

as this is my first post on the SuSanA forum I would like to introduce myself shortly. I am a young Brazilian environmental engineer, graduated at the Universidade Federal de Viçosa, one of the pioneer universities in Brazil in terms of soil and agricultural research. I have focused my studies in Permaculture and Ecological Sanitation and since my graduation I am based in Berlin. At the moment I am working as an upcycling artisan while applying for a post-graduation program in Germany.

From my point of view Terra Preta toilets are as important as UDDTs are. They should not be seen as competitors, but allies. I also don't see the need of having an air tight lid as an obstacle (also UDDTs have special conditions to work properly, like ventilation pipe and insolation). What I like about TPS toilets is that they try to create a better (and safer) soil conditioner as the one from UDDTs.
Only in Brazil there are more than 240 archeological sites where the Anthropogenic Dark Earth - ADE- (or Terra Preta Antropogênica - TPA -, in Portuguese) is being studied. They do cover a great area (ca. 20 000 km²), if one thinks that these spots were used mostly for food production. It is also interesting to say that such figures are only for ADE and they are not taking in consideration the Terra Mulata, which always surrounds the ADE and occurs on a bigger scale. Also these small percentages (0.1 to 0.3%) are just considering the already known spots. I think it is quite impressive to imagine a 100ha field (the area of the Estação Científica Ferreira Penna) that is still as fertile as 500 years ago and is nowadays known as one of the most fertile soils in the world!

As in Amazon Basin rocks or stones are not so common, the índios were forced to find alternative ways to chop down trees without using axes. They had specific ways to burn trees in order to obtain a glade. Based on that, it is easier to understand the char issue. Although it may look strange, cooking with woodgas stoves is high efficient and healthier than cooking with charcoal. And the good thing is that char has many many other properties that improve soil quality (one can find huge books only about that).

The TPS Conference is a good opportunity to discuss about a new theme and to show others a new way of sanitation and biowaste management. Hope to see you there!

Best regards,
Hugo

Dear Ralf and others,

terra preta sounds good, the multi level farming system (trees/shrubs/vegetables) is something that I am even trying to implement in my garden here in Northern Uganda (without trying to mimic terra preta, just found out about these advantages on my own). Something I have never understood about terra preta is the use of all that charcoal in the soil. Can you inform me about that?

Here, charcoal is the most common and preferred fuel for cooking - nobody would think of putting it into the soil, unless we are talking about leftovers from burning wood or chunks of charcoal. And the product of charcoal burning, the ash is also a known fertilizer and can be an ingredient in compost making. And, of course, a useful additive for UDDT toilets. So, why incomplete combustion rather than complete one (which is certainly giving more energy)?

And don't you think terra preta is predominantly something for moist climates? The Amazon region is known to be very wet - I think that helps with the development of humus in the soil. At very high temperatures and more dry conditions, humus has a tendency to degrade very quickly, so that deep humus layers will take a very long time to develop (decades rather than years). And here, I am just talking of up to 30 or 40 cm, not meters!

Cheers, Hanns-Andre

Dear Elisabeth,

Thank you for bringing up the discssion! Terra Preata is antropogenic black soil consiting of organic matter including excreta and charcoal. It covers around 10% of the Amazon region around Manaus, not of all the vast Amazonian Rainforests. We can also call it Black Earth but why should all be in English? This is the inspiration of the probably most sucessful sanitation and biowaste management ever on Earth. In order to honour those Indios we use this name. We can say EcoSan just the same...

Now to TP sanitation. Please show me where the hype is? Hardly anybody works on this so far. The most promising process of lactofermentation is widely ignored. Desiccation does not make sense any more in many cases. In addition we want to compost urine so we do not need diversion any more, luckily. Urine application mimics chemical agriculture and is a dead end road.

For the process: The breakthrough solution to sanitation is lactic acid fermentation. It can be applied in most sanitation systems including pit latrines. It will require simple bacteria strains and simple waste sugars. Also urine storage and desiccation chambers can profit, even if the desiccation chamber ist not closed to he environment or at least covered toward the toilet(what is hygienically not acceptable). Our way of development is a closed container toilet, not diverting urine and pumping out once a week. Very similar to what EAWAG has developed with urine diversion. The logistics are feasible at very reasonable prices and we should forget about people in more densely populates areas dealing with their own excreta. Let us transport where excreta can be converted to Terra Preta or whaterver else to come to material for conditioning non-food land eg for re-forestation. The well proven fact of endocytosis, the direct uptake of living bacteia like E-coli and Salmonella into plants advises us against direct food production in excreta.

We work on systems that can easily serve 100.000 or a Million people also in more urban settings. No doubt that rural houses can have simple arbo loos with urine utilisation but this is not where the sanitation problem is. The TPS conference is to advance sanitation towards integrated solutions including Energy supply. For the first time we have the the beautiful sit-syuat-toilet that won the WTO-Design Award that I would install right away into my own house and that can work in multi storage, too (see www.terra-preta-sanitation.net). We invite especially also critical discussion, only this way we can learn. We need to create solutions for hundreds of millions of people. This is possible now.

Ralf